As long as motor vehicles have been using volatile fuels in tanks carried on the vehicle, there has been a problem with fuel vapors. Gas caps had to have a vent hole in the early days especially when gravity feed of the fuel was used. Later as fuel pumps were used vapor was still a problem since in hot weather or bumper-to-bumper progress, overheating of the gasoline lines would cause vapor lock resulting in an interruption of fuel supply. With the advent of fuel injection, the problem has been alleviated but in hot climates or under certain conditions of ambient temperatures vapor has continued to be a problem. Fuel pumps have been designed with vapor ports to remove vapor in the liquid fuel outlets.
In geographic areas where temperatures reach 90.degree. F. or 120.degree. F. or more, a vehicle standing in the sun will cause vaporization in the top of fuel tanks and also in the fuel lines. Another aspect lies in the environmental problems which require that there be as little as possible of vapor escaping from fuel systems or fuel tanks in normal operation.
Accordingly, the present invention is directed to an automotive vehicle system in which recovery of vapor is accomplished, and, the liquid fuel resulting from the compression of the vapor, is fed back into the fuel line leading to the fuel injection system of the engine.
An object of the invention will also be to provide pressure responsive switches to maintain the functioning of the system, and vapor retaining canisters to collect vapor from a fuel tank and return it to the fuel system in the form of liquid fuel. Another object is the utilization of an engine off-drive for a vapor pump which can be clutch controlled by a pressure responsive switch.